1. Field of the Invention
The present invention relates to a combination service for simultaneously performing two or more services, and particularly, to a terminal, method and system for performing a combination service using terminal capability version information of the terminal.
2. Discussion of the Related Art
A combination service is a service in which two or more services are simultaneously performed between a first user and a second user. The combination service can also indicate a service for combining at least two or more of a first service based upon a first network, a second service based upon a second network, and a third service based upon a third network, and then for simultaneously performing the combined services between two or more users.
In order to perform the combination service between the first and second users, the first and second users need to respectively understand information related to supportable services of the other party and then negotiate available services therebetween.
Among the different types of combination services, a Combination of a CS service and an IMS service (CSI) will now be explained as an exemplary combination service.
The CSI (also referred to herein as CSI service) indicates a service in which a Circuit Switched (CS) service and an IP Multimedia Subsystem (IMS) service are combined (united) with each other and then the combined services are simultaneously performed between two or more users/terminals. In the CSI, an IMS session for an IMS service can be added to a CS call already set between first and second users, or a CS call can be added to an IMS session already set between the first and second users. The IMS service, which may be added to the CS call preset between the first and second users, can include one or more of IMS based services such as an Instant Messaging (IM), a video sharing, a data delivery, etc. One example of the CSI (combination of CS and IMS services) can be carrying out a mobile phone conversation (CS service) between a user at mobile terminal A and another user at mobile terminal B and while talking, transmitting a video clip or pictures (MS service) from the mobile terminal A to the mobile terminal B.
FIG. 1 illustrates a network construction for providing a general combination service, for example, the CSI, between first and second terminals according to a related art. As illustrated in FIG. 1, a general network for providing the combination service such as the CSI can include first and second CS core networks 31 and 32 to support a CS service for the CSI between a first terminal 10 and a second terminal 20, first and second IMS core networks 41 and 42 to support an IMS service for the CSI between the first and second terminals 10 and 20, a first Application Server (AS) 43 connected to the first IMS core network 41 to perform a particular function of the IMS session for the CSI related to the first terminal 10 such as a service based accounting function, a second AS 44 connected to the second IMS core network 42 to perform the particular function of the IMS session for the CSI (e.g., the service based accounting function), a first x-radio access network xRAN 30 for the first terminal 10 to access the first CS core network 31 and the first IMS core network 41 (and vice versa), and a second xRAN 33 for the second terminal 20 to access the second CS core network 32 and the second IMS core network 42 (and vice versa).
The general network for providing the CSI or the like can further include a first Packet Switched (PS) core network 40 connected between the first xRAN 30 and the first IMS core network 41 to set an IMS session of the CSI, and a second PS core network 45 connected between the second xRAN 33 and the second IMS core network 42 to set the IMS session of the CSI.
Each of the first and second CS core networks 31 and 32 can include a Mobile Switching Center (MSC), a Visiting Location Register (VLR), and a Home Location Register (HLR).
A general CSI providing method in the general network of FIG. 1 will now be explained.
For a CS call between the first and second terminals 10 and 20, data and control signals are exchanged therebetween via the first and second CS core networks 31 and 32. For an IMS session, exchange of data and control signals is performed via the first PS core network 40 and the first IMS core network and via the second IMS core network 42 and the second PS core network 45.
The first terminal 10 has a function to simultaneously access the first CS core network 31 and the first PS core network 40, while the second terminal 20 has a function to simultaneously access the second CS core network 32 and the second PS core network 45.
Before initiating the CSI service between the first and second terminals 10 and 20, the first and second terminals 10 and 20 exchange with each other current radio environment information and terminal capability information, and thus respectively obtain information related to supportable services with respect to the other party.
The current radio environment information of the terminal is used as important information required to determine user's activities after setting the CS call. The radio environment information exchange occurs over a CS domain during the CS call setup. The radio environment information is flexible and can be different depending on an environment when the CS call is set. Accordingly, the exchanged radio environment information is used as information valid only during the lifetime of the CS call. The radio environment information may contain information related to whether a terminal can support simultaneous CS and PS services such as the CSI.
The terminal capability information is information identifying capabilities of the terminal, and is used as information for determining whether a user who is in communication with another party would call available services for that party. The terminal capability information exchange occurs over an IMS domain.
FIG. 2 illustrates a general method for exchanging terminal capability information between the first and second terminals 10 and 20 in the general network of FIG. 1.
Referring to FIG. 2, the first terminal 10 sends a Session Initiation Protocol (SIP) OPTIONS message to the second terminal 20, through the first and second IMS core networks 41 and 42, to request capability information of the second terminal 20 (S21). The second terminal 20 then stores address information of the first terminal 10 contained in the received OPTIONS message (S22), and then sends a 200 OK message to the first terminal 10 in response to the SIP OPTIONS message. The 200 OK message contains the terminal capability information of the second terminal 20 (S23).
The first terminal 10 having received the 200 OK message stores the terminal capability information of the second terminal 20 contained in the 200 OK message (S24).
On the other side, in case that the second terminal 20 has received the OPTIONS message from the first terminal 10 but has not sent an OPTIONS (SIP OPTIONS) message to the first terminal 10 for requesting the terminal capability information of the first terminal 10, the second terminal 20 determines to send the OPTIONS message to the first terminal 10 (S25). Upon receiving the OPTIONS message for requesting the terminal capability information of the first terminal 10 from the second terminal 20, the first terminal 10 stores the address information of the second terminal 20 contained in the received OPTIONS message (S26 and S27), and sends a 200 OK message to the second terminal 20 in response to the received OPTIONS message (S28). This 200 OK message contains the capability information of the first terminal 10.
The second terminal 20 then stores the capability information of the first terminal 10 contained in the 200 OK message sent from the first terminal 10 (S29).
Accordingly, the terminal capability information of the first terminal 10 and that of the second terminal 20 exchanged therebetween are stored in the second terminal 20 and the first terminal 10, respectively, so as to provide a fast service setup and to reduce network loads during the subsequent communication therebetween.
According to the related art method discussed above, in order for a particular terminal to obtain terminal capability information of its counterpart terminal, the particular terminal needs to send an OPTIONS message to the counterpart terminal to thus request the terminal capability information of the counterpart terminal, and receive from the counterpart terminal a response message containing the terminal capability information of the counterpart terminal. Based upon this method, the terminal sends an OPTIONS message once (e.g., for a call setup) a counterpart terminal and stores therein the received terminal capability information of its counterpart terminal for subsequent use.
Hence, even in case where the capability information (capabilities) of the counterpart terminal has not changed, the terminal still sends an OPTIONS message once to the counterpart terminal (e.g., for a call setup) to perform the operation of receiving the unchanged terminal capability information of the counterpart terminal. However, it is not necessary since the capability information of the counterpart terminal has not changed and is already stored in the terminal from the previous OPTIONS operation. Further, such an operation may increase the load of the network.
In general, on the other side, the actual capability information related to the terminal may dynamically be updated. Cases in which the terminal capability information (capabilities) may be changed (updated) according to the related art will be explained as follows.
There are three cases in which the actual capability information of the terminal may be changed in that terminal. Namely, there exist a first case where various devices (e.g., a camera, etc.) have dynamically been attached to the terminal and detached therefrom, a second case where the terminal has been registered in an IMS service, and a third case where the terminal has updated its current capability information by downloading a new codec using a downloading service.
After the change of the actual capability information of the terminal, if a cache of the terminal is not updated together due to the power on/off, SIM swap off, time out, and the like, all of which are related to the terminal, then the capability information of the terminal as stored in the cache of that terminal may not accurately reflect the actual capability information (capabilities) of that terminal. Then, since the counterpart terminal receives the stored capability information from the cache of the terminal, the actual capability information of the terminal will not be consistent with the capability information of the terminal as stored in the cache of the counterpart terminal. That is, due to the dynamic change, the actual capabilities of the terminal may not be known to the counterpart terminal.
Accordingly, when the counterpart terminal desires to use a CSI with the terminal later, the counterpart terminal would confirm that the capability information of the terminal has already been stored in the cache of the counterpart terminal, and then immediately send an INVITE message to the terminal after a radio capability exchange therebetween, without performing the sending of the OPTIONS message (i.e., the OPTIONS process) to obtain the capability information of the terminal. The counterpart terminal accordingly requests a PoC service from the terminal. However, since the capabilities of the terminal have changed (e.g., the terminal is not fully capable of performing a PoC service), the terminal de-registers the PoC service, the PoC service fails to be requested, and thereby the counterpart terminal must re-perform the OPTIONS process to obtain the capability information of the terminal. Thus, the previously stored terminal capability information cannot be used in the related art.
In addition, in the current mobile communications system, one subscriber can have multiple terminals, and one public user identity can be used simultaneously at several subscriber identity modules (SIMs) of the terminals. Namely, one subscriber shares a Mobile Station International Subscriber Directory Number (MSISDN) with other terminals for use. In case of a cache which uses only the public user identity, when a request is received, it may not be possible for the receiving terminal to recognize which one of the multiple terminals of the counterpart has sent the request because of the use of the public user identity. Accordingly, the combination service (e.g., the CSI) may not be normally performed with the terminal that has actually sent the request.